Gluteus Medius

Introduction

Introduction to Gluteus Medius

The gluteus medius is a thick, fan‑shaped muscle located on the lateral aspect of the pelvis, deep to the gluteus maximus and superficial to the gluteus minimus. It is the primary abductor of the hip joint and a critical stabiliser of the pelvis during single‑leg stance. Its integrity is essential for a normal, non‑waddling gait. Weakness or dysfunction of this muscle leads to a characteristic Trendelenburg gait and sign, making it one of the most clinically important muscles of the lower limb.

Study

1. Origin and Insertion

The gluteus medius arises from the external surface of the ilium between the anterior and posterior gluteal lines, and from the overlying gluteal aponeurosis. The muscle fibres converge to form a strong tendon that inserts onto the superolateral aspect of the greater trochanter of the femur, passing a bursa (the trochanteric bursa of gluteus medius) that separates it from the bone.

2. Relations

Superficially, the gluteus medius is covered by the gluteus maximus and the deep fascia of the thigh (fascia lata). Deep to it lies the gluteus minimus and the superior gluteal neurovascular bundle (superior gluteal artery, vein, and nerve), which run in the plane between the two muscles. Posteriorly, it is related to the piriformis. Anteriorly, it is adjacent to the tensor fasciae latae. The greater trochanteric bursa separates its tendon from the bone.

3. Nerve Supply

The gluteus medius is innervated by the superior gluteal nerve (L4, L5, S1), which arises from the sacral plexus and enters the muscle on its deep surface.

4. Blood Supply

The muscle receives its blood supply from the deep branch of the superior gluteal artery, a branch of the internal iliac artery. Venous drainage accompanies the artery into the internal iliac vein.

5. Actions

The gluteus medius is the chief abductor of the hip. Its anterior fibres assist in medial (internal) rotation and flexion of the hip, while the posterior fibres assist in lateral (external) rotation and extension. Its most vital role is stabilisation of the pelvis in the coronal plane: during single‑leg stance, the gluteus medius of the weight‑bearing limb contracts powerfully to prevent the pelvis from dropping on the opposite, unsupported side. Without this action, the hip would adduct and the pelvis would tilt.

6. Functional Considerations

The gluteus medius functions isometrically and eccentrically to control pelvic tilt during the stance phase of gait. In addition to walking, it is active during running, jumping, and cutting movements. Weakness leads to the Trendelenburg sign: when standing on the affected leg, the contralateral pelvis drops. The compensatory Trendelenburg gait (or gluteus medius lurch) involves a lateral lean of the trunk over the affected hip to reduce the demand on the weak abductor.

7. Clinical Relevance

Gluteus medius weakness is a common cause of hip, pelvic, and knee pain due to altered biomechanics. It can result from superior gluteal nerve injury, lumbar radiculopathy (L4, L5, S1), or disuse atrophy. Tendinopathy and tears of the gluteus medius tendon (rotator cuff tear of the hip) are a frequent source of greater trochanteric pain, particularly in middle‑aged women. Total hip arthroplasty using a lateral (Hardinge) approach splits the gluteus medius, risking postoperative weakness and Trendelenburg gait. The muscle is also used as a flap for reconstructive surgery. Intramuscular injections in the buttock should be placed in the upper outer quadrant to avoid the superior gluteal nerve.

Summary

Summary of Gluteus Medius

The gluteus medius is a fan‑shaped hip abductor originating from the ilium and inserting on the greater trochanter. Supplied by the superior gluteal nerve and artery, it abducts, medially rotates, and stabilises the pelvis during gait. Weakness produces Trendelenburg's sign and gait. Clinical conditions include tendinopathy, tears, nerve injury, and surgical‑related weakness.